ST. PETERSBURG, FLA. – Both the bidirectional cavopulmonary shunt and the hemi-Fontan procedure have been used in children with hypoplastic left heart syndrome. Is one better than the other?
Dr. Tom Karl, deputy director of pediatric cardiac surgery at Mater Children's Hospital in South Brisbane, Queensland, sought to answer this question at the symposium.
One potential benefit of the bidirectional cavopulmonary shunt, he said, is decreased tricuspid insufficiency as the right ventricle's geometry normalizes from volume unloading.
Other potential benefits include avoidance of later hypertrophy and subendocardial ischemic damage. General hemodynamic stability is promoted by improvement in effective systemic output – with reduced interstage mortality, better somatic growth, and the opportunity to correct associated abnormalities out of the neonatal period, he added.
But is the bidirectional cavopulmonary shunt better than the hemi-Fontan procedure when it is used as the second stage in the typical three-stage treatment sequence (between neonatal palliation, e.g., Norwood procedure, and a Fontan operation) for the univentricular heart?
It does have some advantages: It is technically simpler; it can be performed on a beating heart at normothermia, and off pump in many cases; and it requires no prosthetic material. It also is a good setup for an extracardiac variant of the Fontan operation.
“On the other hand, there is some potential for stenosis, and there is probably some asymmetry of flow in many cases,” said Dr. Karl.
The hemi-Fontan doesn't have asymmetry of flow; there is actually very good flow to the left lung, he said. Also, there is a long, favorable history of this type of anastomosis specifically in hypoplastic left heart syndrome, and the hemi-Fontan provides a good setup for a lateral tunnel Fontan completion. Stenosis risk is minimal.
However, the hemi-Fontan is technically more complex. It requires cardiopulmonary bypass, which some surgeons choose to do using deep hypothermic circulatory arrest, and it may pose greater risk to the sinoatrial node. The hemi-Fontan also requires a considerable load of prosthetic material, but this is not seen as a disadvantage if the procedure follows a Norwood procedure, noted Dr. Karl, who said he had no conflicts of interest.